56

CASE 56


A 27-year-old woman presented to her physician complaining of nervousness, tiredness, and difficulty sleeping. She also commented on her weight loss even though her appetite was good and she experienced little menstrual flow during her last two periods. The physical examination revealed skin that was warm and moist, thinning of the hair, tremor of outstretched hands, exophthalmos, and hyperactive tendon reflexes. The patient also had tachycardia, a widened pulse pressure, and an elevated pulse pressure. Palpation of the neck indicated that the thyroid gland was enlarged. Results from the laboratory showed that free T3 and T4 were elevated and thyroid-stimulating hormone (TSH) was undetectable. The patient was diagnosed with Graves’ disease and was placed on propylthiouracil, an antithyroid drug.



WHAT ARE THE ANATOMICAL CHARACTERISTICS OF THE THYROID GLAND?


The salient characteristics of the thyroid gland are:


• Brownish-red and highly vascular

• Mass of approximately 25 g in adults; slightly larger in females. The gland also enlarges during menstruation and pregnancy.

• Right and left lobes are each approximately 5 cm long and are connected at their inferior poles by the isthmus.


WHAT ARE THE ANATOMICAL RELATIONSHIPS OF THE THYROID GLAND?


To truly know your anatomy is to know who the anatomical neighbors are. In the case of the thyroid gland, its anatomical relationships in the neck are:


• Deep to the sternohyoid, sternothyroid, and omohyoid muscles

• Anterior to C5 through T1 vertebrae

• Isthmus of thyroid lies anterior to the 2nd and 3rd tracheal cartilaginous rings


WHAT IS THE ARTERIAL SUPPLY TO THE THYROID GLAND?


The highly vascular thyroid gland receives its blood supply from the (Fig. 7-23):


• Superior thyroid arteries

• Inferior thyroid arteries

image

FIGURE 7-23 Vasculature of the thyroid gland.


(Drake R, Vogl W and Mitchell A: Gray’s Anatomy for Students. Churchill Livingstone, 2004. Fig. 8.169)


The superior thyroid artery is a branch of the external carotid artery, whereas the inferior thyroid artery arises from the thyrocervical trunk, which issues from the subclavian artery. Occasionally, the thyroid gland also may be supplied by the thyroid ima artery. This artery has multiple origins and has been described, for example, branching from the brachiocephalic trunk, right common carotid artery, aortic arch, and internal thoracic artery. Because of its midline ascension in the neck, the thyroid ima artery is vulnerable to injury when performing midline procedures in the neck.



HOW DO THE THYROID HORMONES REACH THE RIGHT ATRIUM?


The venous blood, which contains the thyroid hormones, is drained by the paired superior, middle, and inferior thyroid veins. The superior and middle veins are tributaries of the internal jugular vein, which then drains into the brachiocephalic vein. The inferior thyroid veins drain into the brachiocephalic veins. Blood then flows from the brachiocephalic veins to the superior vena cava before emptying in the right atrium.



HOW DOES THE THYROID GLAND FORM EMBRYOLOGICALLY?

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Jun 16, 2016 | Posted by in ANATOMY | Comments Off on 56

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